1. Field of the Invention
This invention relates generally to semiconductor wafer handling apparatus and, more particularly, to wafer handling apparatus that can be used in an automated environment. The disclosed apparatus can be used with a robotic arm so that semiconductor wafers can be manipulated without human intervention.
2. Discussion of the Related Art
During the processing of semiconductor substrates or wafers, a multiplicity of routine operations involving large numbers of semiconductor wafer units are involved. For example, unprocessed wafers must be transferred from storage containers known as cassettes to process carriers known as susceptors or boats. Once processed, the wafers must be returned to the storage cassette. These operations have typically been performed by human manipulation in the past. The use of human operators has proven to be less than satisfactory. Particles, such as dandruff and skin, dissipated by humans while manipulating the wafers have caused increasing fabrication problems as the dimensions of integrated circuits become smaller. Breakage can be relatively high due to inefficient handling and the multiplicity of routine operations generates human fatigue with corresponding deterioration of job execution.
In the last few years, a number of robotic arms have been developed and are now commercially available. The robotic arm can execute a multiplicity of gross controllable motions with no decrease in efficiency as a function of repetition rate.
A need has therefore been felt for an apparatus that can be coupled to a robotic arm, is capable of engaging semiconductor wafers and can provide manipulation reliability in excess of the abilities of human operators.